Toroidal regulating device

ABSTRACT

A toroidal regulating device for regulating the torque of a motor vehicle toroidal variator has at least one regulator and a first regulating variable which can be fed back to the regulator. The formation of includes at least one first characteristic quantity for a transmitted torque in the toroidal variator. At least one second regulating variable is capable of being fed back. The formation of the second variable includes at least one second characteristic quantity for a pivoting speed of an intermediate roller of the toroidal variator.

BACKGROUND OF THE INVENTION

The present invention relates particularly to a toroidal regulatingdevice, and more particularly to a device for regulating the torque of atoroidal variator, in particular of a motor vehicle, with at least oneregulator and with a first regulating variable which can be fed back tothe regulator and the formation of which includes at least one firstcharacteristic quantity for a transmitted torque in the toroidalvariator.

“Society of Automotive Engineers, Inc., 2002-01-0586, Full Toroidal IVTVariator Dynamics”, Robert D. Fuchs and Yasuhiko Hasuda, in particularpage 3, column 2, FIG. 6, discloses a generic toroidal regulating devicefor regulating the torque of a toroidal variator of a motor vehicle,with a regulator. A regulating variable formed by a characteristicquantity for a transmitted torque in the toroidal variator can be fedback to the regulator. The determination of the characteristic quantityforming the regulating variable includes a characteristic quantity of apressure in a piston/cylinder unit of the toroidal variator.

An object of the present invention is to provide a toroidal regulatingdevice which, at a generally low outlay in structural terms, allows aparticularly stable regulating behavior with a short adjusting time andwhich, furthermore, is suitable particularly for transmissions with ageared-neutral function.

The present invention is implemented in a toroidal regulating device forregulating the torque of a toroidal variator, in particular of a motorvehicle, by providing at least one regulator and with a first regulatingvariable which can be fed back to the regulator and the formation ofwhich includes at least one first characteristic quantity for atransmitted torque in the toroidal variator.

The present invention is based on the recognition that, in transmissionswith a geared-neutral function, standstill can be brought about onlywhen the step-up is discrete. In the case of stepup-regulated toroidalvariators or with a toroidal regulating device for stepup regulation,the discrete stepup can be set only at high outlay. Withtorque-regulated toroidal variators or with toroidal regulating devicesfor torque regulation, however, standstill in the case of transmissionswith a geared-neutral function can be implemented in a simple way inregulating terms, and therefore toroidal regulating devices for torqueregulation are suitable particularly for transmissions with ageared-neutral function. Moreover, as compared with toroidal regulatingdevices for ratio regulation, toroidal regulating devices for torqueregulation allow a particularly simple and exact variation of thetorque, with the result that these are also particularly suitable fortransmissions having different driving ranges.

By the toroidal regulating device being configured according to theinvention with at least one second feedback regulating variable, theformation of which includes at least one second characteristic quantityfor a pivoting speed of an intermediate roller of the toroidal variator,advantageous damping and consequently a stable system can be achieved atleast largely without a technically implemented castor angle. The centerangle is to be understood as meaning an angle between an intermediateroller mounting or an actuating piston of an intermediate roller and theperpendicular to the central shafts of the toroidal variator. If thecastor angle can be reduced, in particular smaller than 5°, andparticularly advantageously can be set equal to zero or an actuatingpiston of the intermediate roller can be arranged perpendicularly tocentral shafts of the toroidal variator, then, in particular, the outlayin structural terms, i.e., the weight, components and construction spacecan be saved. In the case of a zero castor angle, no pivoting of theintermediate roller can be achieved only in one position, as comparedwith a castor angle unequal to zero. Consequently, a small stroke of theactuating piston can be achieved and energy can be saved. Furthermore,high flexibility, particularly in terms of structural refinements, canbe achieved in a simple way by a variability of individual parameters.

If the determination of the second characteristic quantity includes atleast one characteristic quantity for a rotational speed at the input ofthe toroidal variator and at least one characteristic quantity for arotational speed at the output of the toroidal variator, thenadvantageously sensors usually already present can be utilized andadditional sensors can be avoided. A stepup in rotational speed of thetoroidal variator can be deduced from a quotient of the characteristicquantity of the rotational speed at the input of the toroidal variatorand of the characteristic quantity of the rotational speed at the outputof the toroidal variator. This quantity can then either bedifferentiated directly or, in an intermediate step, first be convertedinto a corresponding pivot angle and subsequently be differentiated. Thecharacteristic quantities for the rotational speeds can either bedetected directly on the toroidal variator via sensors or rotationalspeed values can be used which have been determined elsewhere and makeit possible to determine the rotational speed at the input and at theoutput of the toroidal variator.

Additionally or alternatively, in order to determine the secondcharacteristic quantity, other quantities which seem to be appropriateto a person skilled in the art could also be detected, such as, forexample, directly, an existing pivot angle via which a pivoting speedcan be deduced by differentiation.

In a further refinement of the invention, the second regulating variablecan be the result of a multiplication by at least one proportionalityfactor. Via the proportionality factor, a desired damping can be set ina controlled manner, for example, advantageously, a damping of one, andthe system can be optimized in a simple way. If the proportionalityfactor is dependent on at least one operating variable, such as on anexisting rotational speed, load and/or temperature, etc., in that, forexample, this is read out from a corresponding characteristic map duringa regulating process or is determined via a corresponding analyticalfunction, constant damping can be achieved independently of variousoperating situations and/or damping can advantageously be adapted tovarious operating situations.

Furthermore, the second regulating variable can be fed to a manipulatedvariable of the regulator, this having an advantageous effect on theregulating behavior. In principle, however, the second regulatingvariable could also be capable of being fed to a command variable.

If the determination of the first characteristic quantity includes atleast one characteristic quantity for a pressure in a piston/cylinderunit of the toroidal variator, then cost-effective sensor technology canalso be achieved. For this purpose, either two absolute pressuresensors, i.e., measurement with respect to a vacuum, or two relativepressure sensors, i.e., measurement with respect to an ambient pressureand/or a differential pressure sensor may be employed.

Alternatively, even only one of the two first-mentioned sensors may beused if an already known pressure, for example ambient pressure orsystem pressure, always prevails in one of two chambers of a cylinderfor supporting the intermediate roller. The sensor would in this caseadvantageously be connected selectively, for example via a changeovervalve, to that chamber in which the unknown pressure prevails.

Instead of detecting the pressures via a sensor, these measures couldalso be routed hydraulically in each case to a regulating slide or to aregulating slide valve, with the result that an advantageously lowoutlay in manufacturing terms and high operating reliability can beachieved. If in this case at least one of the regulating slides hasexactly two control edges, the outlay in manufacturing terms can befurther reduced and the manufacturing costs can be lowered as a resultof the reduced tolerance requirements. In this connection reference ismade to unpublished application DE 102 33 089.

Additionally or alternatively, however, a torque at the input of thetoroidal variator, a torque at the output of the toroidal variatorand/or a supporting force on the intermediate roller could also bedetected, for example, by way of force measurement between a holding armof the intermediate roller and an actuating piston.

The regulator may be configured with various regulating elements whichseem appropriate to a person skilled in the art. If, however, theregulator is a PID regulator or is provided at least with an integralelement and a differential element, stationary regulating deviations canadvantageously be avoided by the integral element and an overshoot canadvantageously be avoided by the differential element.

The solution according to the present invention is suitable, inprinciple, for all types of toroidal variators, but, in addition to halftoroidal variators, particularly advantageously for full toroidalvariators in which a castor angle is used in a known way for achievingdamping.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

FIG. 1 is a schematic, partially perspective view of a full toroidaltransmission with a toroidal regulating device according to the presentinvention, and

FIG. 2 is a block diagram of the toroidal regulating device shown inFIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a detail of a diagrammatically illustrated full toroidaltransmission of a motor vehicle, with a toroidal regulating device forregulating the torque of a toroidal variator designated generally bynumeral 11. The toroidal variator 11 comprises an intermediate roller 10which is arranged between two toroidal disks 12, 13 and of which thepivot angle λ between the toroidal disks 12, 13 can be set via ahydraulic actuating unit designated generally by numeral 15. For thispurpose, the actuating unit 15 has a valve block 16, via which apressure difference p1−p2 can be set in a double-acting piston/cylinderunit 17. The piston/cylinder unit 17 is connected to the intermediateroller 10 via a piston rod 18 which is displaceable in the direction ofdouble arrows 19, 20 via an actuating force of the piston/cylinder unit17 the pivot angle λ thereby being capable of being set. The piston rod18 is oriented perpendicularly to central shafts 21, 22 of the toroidalvariator 11. The full toroidal transmission possesses a castor angleequal to zero.

According to the invention, the toroidal regulating device has aregulator G_(R) designed as a PID regulator. A first regulating variableX₁ can be fed back to the regulator. The formation of which firstregulating variable X₁ includes a first characteristic quantity for thetransmitted torque in the toroidal variator 11 (FIG. 2). For thispurpose, a differential pressure in the piston/cylinder unit 17 or aftera first controlled system part G_(S1) can be detected via a sensor unit14 having a differential pressure sensor, a command variable W with adesired pressure sequence being fed, during operation, to the regulatorG_(R) in addition to the first regulating variable X₁.

In addition to the first regulating variable X₁, a second regulatingvariable X₂ can be fed back. The formation of the variable X₂ includes asecond characteristic quantity for a pivoting speed of the intermediateroller 10 of the toroidal variator 11. The determination of the secondcharacteristic quantity includes a characteristic quantity for therotational speed at the input of the toroidal variator 11 or an inputrotational speed of the toroidal variator 11 and a characteristicquantity for a rotational speed at the output of the toroidal variator11 or an output rotational speed of the toroidal variator 11. The inputrotational speed and the output rotational speed can be detected via asensor unit 23 after a second controlled system part G_(S2) (FIG. 2). Aquotient of the detected rotational speeds or a rotational speed stepupis determined via an evaluation unit 24. From the rotational speedstepup, a pivot angle is determined which is subsequently differentiatedin a differential element 25. A pivoting speed determined therefrom isthen multiplied, during operation, by a proportionality factor K whichis dependent on a detected transmission oil temperature and an existingload and is dependent on the input rotational speed of the toroidalvariator 11. For this purpose, the proportionality factor K is read outfrom a known type of characteristic map filed in a memory, (notillustrated).

The second regulating variable X₂ formed from the result of themultiplication is added, during the regulating process, to an auxiliarymanipulated variable Y′ of the regulator. The result of the additionforms a main manipulated variable Y fed to the valve block 16.

1-10. (canceled)
 11. A toroidal regulating device for regulating thetorque of a toroidal variator, comprising at least one regulator a firstregulating variable be fed back to the regulator and the formation ofwhich includes at least one first characteristic quantity for atransmitted torque in the toroidal variator, and at least one secondregulating variable (X₂) which can be fed back, and the formation ofwhich includes at least one second characteristic quantity for apivoting speed of an intermediate roller of the toroidal variator. 12.The toroidal regulating device as claimed in claim 11, wherein thesecond characteristic quantity is determined to include at least onecharacteristic quantity for a rotational speed at the input of thetoroidal variator (11) and at least one characteristic quantity for arotational speed at the output of the toroidal variator.
 13. Thetoroidal regulating device as claimed in claim 11, wherein the secondregulating variable comprises the result of a multiplication by at leastone proportionality factor (K).
 14. The toroidal regulating device asclaimed in claim 13, wherein the proportionality factor is dependent onat least one operating variable.
 15. The toroidal regulating device asclaimed in claim 11, wherein the device is configured such that thesecond regulating variable can be fed to a manipulated variable (Y′) ofthe at least one regulator.
 16. The toroidal regulating device asclaimed in claim 11, wherein the first characteristic quantity isdetermined to include at least one characteristic quantity for apressure in a piston/cylinder unit of the toroidal variator.
 17. Thetoroidal regulating device as claimed in claim 11, wherein the at leastone regulator is designed as a PID regulator.
 18. A method with atoroidal regulating device as claimed in claim 11, comprising forming afirst regulating variable which includes at least one firstcharacteristic quantity for a transmitted torque in the toroidalvariator, feeding back the first regulating variable to the at least oneregulate, forming at least one second regulating variable which includesat least one second characteristic quantity for a pivoting speed of anintermediate roller (10) of the toroidal variator (11), and feeding backto at least one second regulating variable to the at least oneregulator.
 19. The method as claimed in claim 18, the at least onesecond regulating variable is fed to a manipulated variable of theregulator (G_(R)).
 20. A toroidal transmission with a toroidalregulating device as claimed in claim 11, further comprising a castorangle smaller than 5°.